On Tue, Jul 09, 2019 at 12:00:05PM -0700, Matthias Kaehlcke wrote: > Backlight brightness curves can have different shapes. The two main > types are linear and non-linear curves. The human eye doesn't > perceive linearly increasing/decreasing brightness as linear (see > also 88ba95bedb79 "backlight: pwm_bl: Compute brightness of LED > linearly to human eye"), hence many backlights use non-linear (often > logarithmic) brightness curves. The type of curve currently is opaque > to userspace, so userspace often uses more or less reliable heuristics > (like the number of brightness levels) to decide whether to treat a > backlight device as linear or non-linear. > > Export the type of the brightness curve via the new sysfs attribute > 'scale'. The value of the attribute can be 'linear', 'non-linear' or > 'unknown'. For devices that don't provide information about the scale > of their brightness curve the value of the 'scale' attribute is 'unknown'. > > Signed-off-by: Matthias Kaehlcke <mka@xxxxxxxxxxxx> I wonder what kind of problem you are solving here. Can you describe that in a few words? Best regards Uwe -- Pengutronix e.K. | Uwe Kleine-König | Industrial Linux Solutions | http://www.pengutronix.de/ | _______________________________________________ dri-devel mailing list dri-devel@xxxxxxxxxxxxxxxxxxxxx https://lists.freedesktop.org/mailman/listinfo/dri-devel
